A fluorescent throat spray that pinpoints abnormal cells could help doctors spot early oesophageal cancer, research has shown.
The disease, which killed 'Morse' star John Thaw, can easily be missed, or wrongly diagnosed, in its early stages.
Often patients are given unnecessary invasive treatment, including removal of the oesophagus -- the "food pipe" that connects the throat to the stomach.
The new technique involves spraying a fluorescent dye into the oesophagus that attaches to normal, healthy cells. The dye cannot stick to cancer cells, or those turning malignant.
Abnormal cells stand out from healthy cells that glow green under light of a specific wavelength. They can then be seen with an endoscope -- a flexible optical device -- passed down the oesophagus.
Affected areas can be treated with radiofrequency ablation, a minimally invasive method of killing cancer cells using electrical current.
Dr Rebecca Fitzgerald, from the Medical Research Council Cancer Cell Unit in Cambridge, who led the study published in the journal 'Nature Medicine', said: "Current methods to screen for oesophageal cancer are controversial -- they are costly, uncomfortable for the patient, and are not completely accurate. "This could spare patients radical surgery to remove the oesophagus that can result in having to eat much smaller more regular meals and worse acid reflux."
After pilot studies on large numbers of tissue samples, the spray was tested on four patients in the process of having early cancer removed.
In two cases, the spray revealed hidden pre-cancerous areas that had evaded detection by conventional imaging.
Another patient whose entire oesophagus had been removed was shown to have undergone unnecessary treatment.
Professor Kevin Brindle, from Cancer Research UK's Cambridge Research Institute, said: "The benefit of using this dye is that it is specific, relatively cheap and is unlikely to cause any unwanted effects at the levels we use."
The chief risk factors for oesophageal cancer include alcohol use and smoking.